Case Report East African Orthopaedic Journal TRANSVERSE FRACTURE IN A TEN YEAR OLD BOY: CASE REPORT

B.M. Ndeleva, MMed Ortho (Mak), FCS (Ortho) ECSA, Orthopaedic Surgeon & Lecturer, Egerton University, Njoro, Kenya. C.K. Lakati, FCS (Ortho) ECSA, Orthopaedic Surgeon & Lecturer, Egerton University, Njoro, Kenya, M.L. Lutomia, FCS (Ortho), ECSA, Orthopaedic Surgeon & Lecturer, Egerton University, Njoro, Kenya and S.O. Mak’Anyengo , MBChB (Pret), COSECSA, Resident, Rift Valley Provincial General Hospital, Nakuru, Kenya

Correspondence to: Dr. B. M. Ndeleva, P.O. Box 1562 - 90100, Machakos, Kenya. Email: [email protected]

ABSTRACT

Patella fractures are rare in children. Transverse fractures in particular are an uncommon pattern. We report a case of a transverse patella fracture in a ten year old boy. He presented with inability to actively extend his left , two months after a fall. On evaluation he was found to have a transverse fracture of his left patella. This was treated by tension band wiring. INTRODUCTION Figure 1 AP and lateral view radiographs of the patient’s left The function of the patella is to increase the mechanical knee advantage of the quadriceps by increasing the angle at which the quadriceps acts. In children a larger part of the patella is cartilaginous compared to adults. It is also a lot more mobile and therefore less predisposed to fracturing (1,2). As more and more of the patella ossifies, the incidence of fractures of the patella increases. The pattern too changes. While the sleeve fracture is the commonest pattern seen in young children, adolescents will have other patterns including transverse and comminuted fractures just as in the adults (1, 2). We are not aware of any reported case(s) of patella fracture(s) in children in local literature.

CASE REPORT Figure 2 AP and lateral view radiographs of the patient’s right A ten year old boy presented at the Rift Valley (normal) knee Provincial General Hospital, Nakuru two months after he fell on his left knee. He presented with inability to actively extend his left knee. Immediately after the fall, he reported that he had pain and swelling which resolved after about two weeks. However the inability to extend his knee had persisted. On examination, there was wasting of the quadriceps muscles and a palpable gap within the patella. The patient could not extend the affected knee actively. The rest of the was normal. Radiographs revealed a transverse fracture of the patella as shown in Figure 1. Figure 2 shows the radiographs of the patient’s right (normal) knee.

64 EAOJ; Vol. 7: September 2013 East African Orthopaedic Journal The patient was treated by open reduction and internal patella fracture. fixation of the patella fracture with a tension band wire When a patella fracture is suspected, plain using 1.6mm k-wires and gauge 18 cerclage wire and is the mainstay of investigation. Anteroposterior and the limb splinted in a back slab. lateral view radiographs are the standard. The knee should be flexed to 30 degrees when taking the lateral Figures 3 and 4 view to best demonstrate any displacement (7, 10). For The patient’s post-operative check radiographs displaced fractures through the substance of a fully ossified patella, the diagnosis is usually obvious on good radiographs. For transverse fractures, as the one we are reporting, a gap is most obvious on the lateral view. Scrutiny of the anteroposterior view too reveals a gap though the superimposed distal may make it harder to appreciate the fracture. Longitudinally oriented fractures are best seen on the skyline view (10). Non-displaced patellar fractures are easily missed on plain radiographs. For such, an MRI is the investigation of choice (5, 11, 12). MRI is also the only way in which the size of the chondral fragment in the sleeve fractures can be determined pre-operatively. It should therefore be considered for all patients in whom the doctor highly DISCUSSION suspects a fracture but has normal plain radiographs and in all paediatric patients with an avulsion fractures Patella fractures are rare in children. Schmal et al of the lower pole of the patella to check for a sleeve (1) reported an incidence of 0.44% amongst children fracture. and adolescents. Most of the fractures were in older Knowledge of the ossification pattern around the children with none seen before the age of 8 years. Of knee as well as normal variants is essential so as these fractures, sleeve fractures are the commonest to distinguish fractures from other anomalies such accounting for about 60% of all paediatric patella as bipartite patella and Sinding-Larsen-Johanssen fractures (2). They were first reported by Houghton and disease (13). Ackroyd in 1979 (3). Transverse fractures, fractures of Patella fractures are considered to be displaced if the poles and comminuted fractures of the patella are the articular step off or separation of the fragments is less common in children (1, 2, 4, 5). These patterns greater than 3mm (5). Non-displaced fractures of the are commoner in adolescents in whom a greater part patella can be treated non-operatively with a splint/ of the patella has ossified. Overall, boys have a higher brace for two to four weeks depending on the age of incidence of patella fractures than girls (1, 2). the patient. Displaced fractures are treated operatively. Causes of patella fractures in children include direct The aims are to restore continuity of the extensor force onto the patella with the patella being crushed mechanism, restore joint congruency and maintain against the distal femur. Most of these injuries occur patella height (1, 2, 6). during sporting activities (6). Another cause of patella Open reduction is done and the reduction held with fractures is indirect forces such as forceful contraction either Tension Band Wire (TBW), modified tension of the quadriceps while the knee is flexed. This results in band wire or a circumferential cable for comminuted avulsion fractures of the patella (6, 7). Stress fractures fractures. Osteosynthesis with lag screws has also have also been reported as a result of repetitive forces been described. For sleeve fractures and other avulsion (8, 9). fractures in which one of the fragments is too small, Whatever the cause, patients complain of a variable transosseous sutures may be used (1, 10). For polar degree of pain and swelling. They may also complain of fractures, all effort should be made to conserve all but inability to extend their knee actively. On examination, the smallest of polar fragments as it has been shown there may be a variable degree of swelling and that long term outcome is superior where the polar tenderness. The proximal portion of the patella may fragments are retained as compared to when they are be high-riding (patella alta) in patients in whom the resected (14). extensor mechanism has been completely disrupted. After the period of immobilization for non-displaced The patient may be unable to actively extend the knee fractures and once pain allows for fractures treated as a result of disruption of the extensor mechanism or operatively, the patient should undergo physiotherapy on account of pain. However, even with a fracture, just as is recommended for adults (15). This includes active range of motion may be maintained as long as knee range of motion exercises and quadriceps the retinaculum is not disrupted. This is usually painful strengthening exercises. The goal is to regain the pre- in the acute phase (5). Therefore, presence of active injury level of function. extension should not be misconstrued to preclude a EAOJ; Vol. 7: September 2013 65 East African Orthopaedic Journal REFERENCES 9. Iwaya, T. and Takatori, Y. Lateral longitudinal stress fracture of the patella: Report of three cases. 1. Schmal, H., Strohm, P. C., Neimeyer, P. et al J. Pediat. Orthop. 1985; 5:73-75. Fractures of the patella in children and adolescents. 10. Beaty, J. H. and Kumar, A. Fractures about the Acta Orthop. Belg. 2010; 76(5):644-650. knee in children. J. Joint Surg. Am. 1994; 2. Dai, L.Y. and Zhang, W. M . Fractures of the 76(12):1870-1880. patella in children. Knee Surg, Sports Traumatol. 11. Bates, D. G., Hresko, M. T. and Jaramillo, D. 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